Chromium is a mineral the body needs in very small amounts, but it plays a significant role in human nutrition. Chromium's most important function in the body is to help regulate the amount of glucose (sugar) in the blood. Insulin plays a starring role in this fundamental biological process, by regulating the movement of glucose out of the blood and into cells. Scientists believe that insulin uses chromium as an assistant (technically, a
cofactor
) to "unlock the door" to the cell membrane, thus allowing glucose to enter the cell. In the past, it was believed that to accomplish this the body first converted chromium into a large chemical called glucose tolerance factor (GTF). Intact GTF was thought to be present in certain foods, such as Brewer’s yeast, and for that reason such products were described as superior sources of chromium. However, subsequent investigation indicated that researchers were actually creating GTF inadvertently during the process of chemical analysis. Scientists now believe that there is no such thing as GTF. Rather, chromium appears to act in concert with a very small protein called low molecular weight chromium-binding substance (LMWCr) to assist insulin's action. LMWCr does not permanently bind chromium and is not a likely source of chromium in foods.
83-85

Based on chromium's close relationship with insulin, this trace mineral has been studied as a treatment for diabetes. The results have been somewhat positive: it seems fairly likely that chromium supplements can improve blood sugar control in people with diabetes. Chromium also might be helpful for milder abnormalities in blood sugar metabolism. One study suggests that chromium might aid in weight loss, as well, but other studies failed to find this effect.

Requirements/Sources

Requirments

The official US recommendations for daily intake are as follows:

Infants

0-6 months: 0.2 mcg

7-12 months: 5.5 mcg

Children

1-3 years: 11 mcg

4-8 years: 15 mcg

Males

9-13 years: 25 mcg

14-50 years: 35 mcg

50 years and older: 30 mcg

Females

9-13 years: 21 mcg

14-18 years: 24 mcg

19-50 years: 25 mcg

50 years and older: 20 mcg

Pregnant Women

18 years or younger: 29 mcg

19 years and older: 30 mcg

Nursing Women

18 years or younger: 44 mcg

19 years and older: 45 mcg

Food Sources

The National Institutes of Health's Office of Dietary Supplements offers this list of food sources for chromium:
110

Food

Serving size

Chromium content
(microgram [mcg])

Broccoli

½ cup

11

Grape juice

1 cup

8

English muffin, whole wheat

1

4

Potatoes, mashed

1 cup

3

Garlic, dried

1 teaspoon

3

Basil, dried

1 tablespoon

2

Beef cubes

3 ounces

2

Orange juice

1 cup

2

Turkey breast

3 ounces

2

Whole wheat bread

2 slices

2

Red wine

5 ounces

1-13

Apple

1 medium

1

Banana

1 medium

1

Green beans

½ cup

1

Chromium is also found in drinking water, especially hard water, but concentrations vary widely. Many good sources of chromium, such as whole wheat, are depleted of this important mineral during processing. The most concentrated sources of chromium are brewer's yeast and calf liver. Two ounces of brewer's yeast or 4 ounces of calf liver supply between 50 mcg and 60 mcg of chromium.

Chromium Deficiency

Some evidence suggests that chromium deficiency may be relatively common.
1,86
However, this has not been proven, and the matter is greatly complicated by the fact that we lack a good test to identify chromium deficiency.
2

Severe chromium deficiency has only been seen in hospitalized individuals receiving nutrition intravenously. Symptoms include problems with blood sugar control that cannot be corrected by insulin alone.

Corticosteroid treatment may cause increased chromium loss in the urine.
3
It is possible that this loss of chromium may contribute to corticosteroid-induced diabetes.

Chromium Absorption

Therapeutic Dosages

The dosage of chromium used in studies ranges from 200 mcg to 1,000 mcg daily, mostly in the form of chromium picolinate. However, there may be potential risks in the higher dosages of chromium (see
Safety Issues
).

Note:

These and all other dosages of chromium regard the amount of the actual chromium ion in the supplement (“elemental chromium”), discounting the weight of the substances, such as picolinate, attached to it.

Some products state that they contain “GTF chromium.” Some of these products are manufactured from brewer’s yeast, which was once thought to contain GTF. Others contain chromium as chromium nicotinate, which bears a faint resemblance to the proposed GTF molecule. However, since GTF is no longer believed to exist, this claim should be disregarded.

Therapeutic Uses

Chromium has principally been studied for its possible benefits in improving blood sugar control in people with
diabetes
. Several, but not all, studies suggest that people with adult-onset (type 2) diabetes may show some improvement when given appropriate dosages of chromium.
5,43,44,45,47-48,102
One study suggests that chromium may also be useful for diabetes that occurs during
pregnancy
.
6
In addition, nondiabetic individuals with mildly impaired blood sugar control might attain better control of blood sugar with chromium supplementation.
7-10
Since mild impairment of blood sugar control is believed to increase risk of heart disease, chromium supplementation might help reduce heart disease rates.

Chromium has been sold as a "fat burner" and is also said to help build muscle tissue. However, most studies evaluating chromium's ability to promote
weight loss
have not found benefits.
11-21,104
One study failed to find benefit with a combination of chromium and
conjugated linoleic acid
.
107

Studies evaluating chromium as a
performance enhancer
or aid to bodybuilding have yielded almost entirely negative results.
23-31,87

Studies on whether chromium can improve
cholesterol
levels have returned mixed results.
32-40
However, one study suggests that chromium combined with
grape seed extract
might have a beneficial effect.
41
In addition, among individuals taking beta-blockers, chromium may raise levels of HDL ("good") cholesterol.
42

When depression is characterized by rapid mood changes, excessive sleeping and eating, a sense of leaden paralysis, and extreme sensitivity to negative life events, the condition is called “atypical depression.” A very small (15 participants) double-blind, placebo-controlled study found that
chromium picolinate
might be helpful for this form of
depression
;
46
however, a much larger study failed to find statistically significant benefits.
97

According to some researchers, impaired blood sugar control, high cholesterol, weight gain, and high blood pressure are all part of a bigger picture, called
metabolic syndrome
, or syndrome X. Since chromium may be helpful for the first three of these conditions, chromium deficiency has been proposed as the cause of syndrome X. However, this has not been proven.

One study failed to find that chromium picolinate at 200 mcg/day can improve symptoms of polycystic ovaries (a common cause of
infertility
).
98

What Is the Scientific Evidence for Chromium?

Diabetes

The evidence regarding use of chromium for type 2 (adult onset)
diabetes
, as well as other forms of diabetes, remains incomplete and inconsistent.

In a
double-blind, placebo-controlled study
, 180 people with type 2 diabetes were given placebo, 200 mcg of chromium picolinate, or 1,000 mcg chromium picolinate daily.
43
The results showed that HbA1c values (a measure of long-term blood sugar control) improved significantly after 2 months in the group receiving 1,000 mcg and in both chromium groups after 4 months. Fasting glucose (a measure of short-term blood sugar control) was also lower in the group taking the higher dose of chromium.

A double-blind trial of 78 individuals with type 2 diabetes compared two forms of chromium (brewer's yeast and chromium chloride) against placebo.
44
This rather complex crossover study consisted of four 8-week intervals of treatment in random order. The results in the 67 participants who completed the study showed that both forms of chromium significantly improved blood sugar control.

Positive results were also seen in three other double-blind, placebo-controlled studies enrolling a total of more than 130 people with type 2 diabetes.
45,95,101-102
However, several other studies have failed to find benefit for people with type 2 diabetes.
47-48,99,105
These contradictory findings suggest that the benefit, if it really exists, is small at best.

A combination of chromium and biotin might be more effective. Following positive results in a small pilot trial,
103
researchers conducted a double-blind study of 447 people with poorly controlled type 2 diabetes.
106
Half the participants were given placebo and the rest were given a combination of 600 mcg chromium (as chromium picolinate) along with 2 mg of
biotin
daily. All participants continued to receive standard oral medications for diabetes. Over the 90 day study period, participants given the chromium/biotin combination showed significantly better glucose regulation than those given placebo. The relative benefit was clear in levels of fasting glucose as well as in HgA1c.

One placebo-controlled study of 30 women with
pregnancy
-related diabetes found that supplementation with chromium (at a dosage of 4 mcg or 8 mcg chromium picolinate for each kilogram of body weight) significantly improved blood sugar control.
49

Chromium has shown a bit of promise for treating diabetes caused by
corticosteroid
treatment.
50,51

Improved Blood Sugar Control in People Without Diabetes

Many people develop impaired responsiveness to insulin (insulin resistance) and mildly abnormal blood sugar levels. A few small, double-blind trials have found that chromium supplementation may be helpful,
52-55
although two studies found no benefit.
56,100
Another small double-blind trial found that chromium improved the body's response to insulin among overweight people at risk of developing diabetes.
57
There is growing evidence that mildly impaired blood sugar control increases the risk of heart disease, suggesting that chromium supplementation might be useful. (See the section below on
Heart Disease Prevention
.)

Weight Loss ("Fat Burning")

The evidence is mixed on whether chromium is an effective aid for
reducing weight
or improving body composition (improving the ratio of fatty tissue to lean tissue).

In one study, 219 people were given either placebo or 200 mcg or 400 mcg of chromium picolinate daily.
58
Participants were not advised to follow any particular diet. Over a period of 72 days, people taking chromium experienced significantly greater weight loss than those not taking chromium, more than 2-½ pounds versus about ¼ pound. Interestingly, people taking chromium actually gained lean body mass, so the loss of fatty tissue was even more dramatic: more than 4 pounds versus less than ½ pound. However, a very high dropout rate makes the results of this study somewhat unreliable.

However, in another double-blind study by the same researcher, 130 moderately overweight people attempting to lose weight were given either placebo or 400 mcg of chromium daily.
59
At the end of the trial, no statistically significant differences in weight or body composition were seen between groups. Researchers were able to show benefit only by resorting to fairly complicated statistical maneuvers.

In a third study, 44 overweight women were given either placebo or 400 mcg of chromium per day.
60
All participants were placed on an exercise program. Over a period of 12 weeks, no differences were seen between the two groups in terms of body weight, waist circumference, or percentage body fat. A small double-blind trial of older women undergoing resistance training also failed to find evidence of benefit.
92
Generally negative results have been seen in other small double-blind trials as well.
61-66, 104,109

When larger studies find positive results and smaller studies do not, it often indicates that the treatment under study is only weakly effective. This may be the case with chromium as a weight-loss treatment.
93
If chromium is effective for weight loss, one small study suggests it may work by influencing the brain and its role in appetite and food cravings.
108

In support of this, an observational trial found associations between higher chromium intake and reduced risk of heart attack.
75

Safety Issues

Although the precise upper limit of safe chromium intake is not known, it is believed that chromium is safe when taken at a dosage of 50 mcg to 200 mcg daily.
88
Side effects appear to be rare.

However, chromium is a heavy metal and might conceivably build up and cause problems if taken to excess. There is one report of kidney, liver, and bone marrow damage in a person who took 1,200 mcg to 2,400 mcg of chromium for several months; in another report, as little as 600 mcg for 6 weeks was enough to cause damage.
77,78
Such problems appear to be quite rare, and it is possible that these individuals already had health problems that predisposed them to such a reaction. The risk of chromium toxicity is believed to be higher in individuals who already have liver or kidney disease.
88

Nonetheless, based on these reports, it’s possible that the dosage of chromium found most effective for individuals with type 2 diabetes—1,000 mcg daily—might present some health risks. For example, there is some evidence that if chromium is taken in high enough amounts, it may be converted from its original safe form (chromium 3) into a known carcinogen, chromium 6.
96
We advise seeking medical supervision before taking more than 200 mcg of chromium daily.

Also, keep in mind that if you have diabetes and chromium is effective, you may need to cut down your dosage of any medication you take for diabetes.
79
Medical supervision is advised.

There are also several concerns about the picolinate form of chromium in particular.
Picolinate can alter levels of neurotransmitters.
89
This has led to concern among some experts that chromium picolinate might be harmful for individuals with
depression
,
bipolar disease
, or
schizophrenia
.
81
There has also been one report of a severe skin reaction caused by chromium picolinate.
80

Finally, there are also concerns, still fairly theoretical and uncertain, that chromium picolinate could cause adverse effects on DNA.
82,90,91,94

The maximum safe dosage of chromium for women who are pregnant or nursing and for individuals with severe liver or kidney disease has not been established.

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